以下坡式單形法匹配近場重建光波導折射率分布

Abstract

本論文之目的在研究擴散式光波導折射率的重建，主要方式是假設一二維折射率模型，寬度方向為誤差函數分布，深度方向為高斯函數分布，再利用下坡式單形法找出最接近實際量測電場的三個模型參數，而重建出折射率分布。 在驗證方面，使用重建的折射率模型代入套裝軟體以計算方向耦合器的耦合長度，並在同一製程製作直波導與方向耦合器。量測結果顯示理論與實驗的耦合長度誤差在10%以內。

Refractive index profile reconstruction of diffused optical waveguides is presented. The process starts with an index model that is a product of an error function for the width direction and a Gaussian function for the depth direction, and then the field distribution is solved numerically. Using the down-hill simplex method, three parameters of the index model are obtained by best fitting the measured near-field distribution. To check the accuracy of the index profile, straight waveguides and directional couplers are fabricated under the same process condition. Then the coupling lengths are measured and compared with those simulated by available software with the reconstructed index profiles. The results show the errors are within 10%.